Apparatus for method for treating wells



Dec. 5, 1961 c. B. HoLT APPARATUS AND METHOD FOR TREATING WELLS 2Sheets-Sheet 1 Filed July 28, 1958 nl ltr x Dec. 5, 1961 c. B. HoLTAPPARATUS AND METHOD FOR TREATING WELLS 2 Sheets-Sheet 2 Filed July 28,1958 INVENTQR CLAREN CE B. HOLT BY Mm., 0%# MA! 4 A O Viagra/ra al ag l@A0 IO Q ,g4/IA,

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ATTORNEYS' United States Patent O 3,011,548 APPARATUS AND METHOD FORTREATING WELLS Clarence B. Holt, 621 Austin, Borger, Tex. Filed July 28,1958, Ser. No. 751,417 7 Claims. (Cl. 166-42) The present invention isan improved means and method for treating wells, and more speciically, amethod and means involving selectively closing the perforations in anoil well casing, by small balls or spheres of appropriate size, whichare lowered to position for application to the perforations, by astructure which forms an important part of the invention.

An important object of the invention is to provide mechanical means forretrieving all of the balls or spheres which have been applied to theperforations to close same, so that they may be examined upon removalfrom the well, to detect as by scratches, ridiging and marking on theballs or spheres, such information as the number of such'balls orspheres which were seated in the perforations and thus to determine howmany of the perforations were closed oif during the formation treatingoperations which were carried out.

A principal object of the invention is to introduce the balls forclosing the perforations, in a basket or cage which is mechanicallylowered to position adjacent the perforations in the casing, asdistinguished from previous practices where such balls have been addedto the stream of treating fluid which is introduced into the casing. Inthese prior practices, where the balls have been introduced into thewell in the casing head along with and into the formation-treatingliquid or material, there is no adequate control of the delivery of theballs to the perforations which it is desired to close ol, nor was thereany adequate provision for removing the balls from the perforations inorder that they might be examined to determine effectiveness of theformation-treating operations which were being carried out.

In order to carry out the purposes of the invention, I have devised astructure comprising a basket to be attached to the lower end of an oilwell tubing or the like, which is of a size to carry a multitude of theperforationclosing balls. This basket is of such construction that lluidmay be introduced downwardly through the tubing, to remove the ballsfrom the basket at the proper location. These operations, involvingproper positioning of "ice for the abovepurpose in order that they maybe ex-A amined to determine the number of perforations which have beentreated 'by entry into same of the treating uid. Furthermore, whenemploying previous practices,

it has not been possible to introduce a sucient number of balls forcomplete closure of all perforations in an oil well casing, and tothereafter treat by fluid injection into the open uncased hole which maylie beneath the casing, at least'with any certainty, and without excessuse of and Waste of the treating iluid. In past practices, no provisionwas made for the use of a conduit for the treating fluid, which wouldpass below the casing perforations closed by the balls, in order tointroduce this iluid into au uncased and lower portion of the drilledhole.

In the drawings, which illustrate the preferred embodiments of apparatusfor practicing the invention:

FIGURE l illustrates conventional well head equip# ment, and shows theball cage of the invention positionedon a tubing string being loweredinto the casing of thev well. Y f

FIGURE 2 is an enlarged partial vertical sectional view through thecasing of the well, at the perforated zone thereof, and which shows theball cage positioned below the perforations and the manner of elevatingthe balls into position to enter the perforations in the cas- ]ng, v

FIGURE 3 is a similar vertical sectional view, showing how the ballsclose off the casing perfor-ations, and further illustrating the mannerof treating an open hole below the casing. 1

FIGURE 4 is a partial vertical sectional view of the cage, showing themanner in which the balls are carried in the cage., v

FIGURE 5 is a side elevational view, partly in section,

l of a modification of the invention, showing how an addithe ballsadjacent to and below the perforations, and f t their removal from thebasket and delivery to the perforations to be closed, may be carried outsubstantially independently of the introduction of the treating fluidinto the well, the latter being introduced at the well head into thespace between the casing and the tubing, and passing downwardly in thisannulus and outwardly through the perforations being treated.

Modern methods for completing oil and gas wells trequently demandtreatments of the producing formations by forcing into the same underhigh pressure, certain acid or fracturing fluid, and this fluid isforced into the formation through the perforations which have beenprovided in the producing casing, in a manner which is well known in theart. In carrying out these procedures, it has been tional section may beaddedv to the cage, to increase its capacity. f

Referring to FIGURE l, the usual oil well outer-or surface casing isshown at `10, and mounted on'top of the same is the customary casinghead 12. Suspended from the casing head 12 as by the conventional hangeris the inner casing 14, and mounted -at` the upper end of this casing isa further casing or tubing head 16. A blow-out preventer 18v or otheritem of control equipment may be mounted on the casing head 116, land astring of tubing 20 passes through the control equip-ment and down intothe( casing of the well, as shown in FIGURE l. -It is at the lower endof the tubing string 201, that the ball cage C which forms an importantpart olfithe invention may be u mounted. 1- f Referring now to FIGURE 2,the lowermost section of'` the tubing string 20 is exteriorly threadedas at 22, and? these threads engage and secure to interior threads on adepending collar 24 which forms the lower end ofthe ball cage C. Theupper portion A2,6 of the ball cage is enlarged, and is cylindrical inform, and is of diameter only slightly less than the interior diameterof the casing 14. This enlarged part .26 of the cage, with the outsidewall of the tubing 20, from which it is spaced, forms a chamber 28 tocarry any number of balls or spheres which are used to close theperforations in the casing. The enlarged part 26 of the cage has abottom wall 30, where it connects with the collar-like extension 24, andthere are a number of vertical openings 32 in this bottom wall, whichopenings are of diameter somewhat smaller than the balls or spheres B,which are disposed in the cage, yas hereinafter described.

In FIGURE 2, the casing 14 is shown lowered to the bottom of the drilledhole, and it may be cemented off at its lower end, in accordance withknown practice. At a selected distance upwardly from the lower end ofthe casing, there is a perforated area 34 formed by shooting orotherwise providing a number of openings or perforations 36, whichextend through the casing and outwardly into the producing formation, asat 38, passing through any cement which may surround the casing at thispoint, or passing outwardly through the formation to the desireddistance, if no cement is present. It is through these perforations thatthe oil or gas, under its natural pressure, is permitted to enter thecasing, during the period when the well is producing, and this oil orgas may be taken from the well through appropriate outlets from thecasing 14, at the well head, or through a ow tubing, with the assistanceof whatever conventional equipment as may be required for the eflicientowing of the well.

As is well known in the art, the perforations in the casing may becomepartially or completely clogged, due to the accumulation of materialstherein, and the channels of flow from the formation outwardly of theperforations may likewise become clogged.V 'It is for this reason, thatvarious methods have been employed, to treat the perforations inthecasing and the passages in the formation, with acid or other fracturinguid in order to 'facilitate the flow of oil and gas from the formation,

The cage C has, in addition to the bottom openings 32, a plurality ofopenings 40 in its side wall, so that when the cage has been lowered tothe desired position adjacent to and below the perforations in thecasing, any uid, such as water or treating fluid, may be pumpeddownwardly vthrough the tubing and out the lower end thereof as shown bythe arrows in FIGURE 2. When this is done, there is created an upwardcirculation of fluid, from the lower end of the tubing, and it passesthrough the openings 32 and 40 in the cage, and as it moves upwardly,thence to elevate the balls B from the cage, to a position adjacent theperforations in the casing. At the same time, by appropriate pumpingmeans at the surface of the well, the treating fluid may be forceddownwardly in'the space 42 between the casing and the tubing, and thistreating iluid will be forced outwardly through theperforations in thecasingand in the formation when the pumping pressure is greater than thenatural pressure in the formation. The balls B which have been elevatedfrom the cage, will be carried `by this outwardly moving fiow of thetreating fluid, into the inner ends of the perforations in the casing,to close off these perforations as it is illustrated by the balls B1 inFIGURE 2.

As is well known in the art, the balls so positioned and delivered willtend to close the more active of the perforations, thus increasingpressure on the perforations which `are less active, or substantiallyentirely clogged, and the tendency of the treating fluid under pressurein the casing area 42 will beto open the less active perforations, bythe intensified pressure thereon. Of course, various pro cedures landmanipulations of the equipment may be carried out, as desired, in orderto treat the formation as desired.

InFIGURE 2, I have shown only a relatively few of the balls B in thecage, and disposed above same, merely for purposes of clarity, but it.will be understood that a relatively great number of such balls orspheres may be carried in the cage, as is better illustrated in FIGURE4. With reference to FIGURE 4, it will be noted that the bottom openings32 are olset outwardly toward ythe outer wall of the basket compartment28, so that it is not possible for the balls to close off the bottomopenings 32.

When using an oil well casing of 51/2 inches outside diameter, and `a2-inch tubing, the basket should be of suicient size to hold up to 200`balls of a diameter of approximately 7A; inch. It will be understoodthat the balls will be of diameter sufliciently greater than theopenings or perforations in the casing, so that they will not `actuallyenter these perforations, `and will not become so embedded therein, thatthey cannot be removed, as hereinafter mentioned.

Referring again to FIGURE 2, the cage C is open at its upper end, asindicated at 44, and the ledge 46 a-t its upper end is of such diameterwith relation to the interior diameter of the casing, that when the cageis elevated on the tubing, after `the treating operation has beencompleted, this ledge 46 will tend to strip the balls from theperforations in the casing, and they will drop into the open end of thecage and can then be elevated from the well, in order that the balls maybe examined to determine the success or degree of treatment of the well,with the treating fluid.

In FiGURE 5, a modied construction of the cage is illustrated, whereinthe upper end 48 of a cage section Si) is threaded, and secured theretoa further section 52 ot' the cage, to increase the overall-capacitythereof, in order that a greater number of balls may be carried, ininstances wherel it may be desired to close off sections of a casing,having a relatively great number of perforations therein.

In FIGURE 3, the casing well is shown as having an open hole H extendingbelow the lower end of the casing 14, which has the perforated area 34in alignment with the oil-bearing stratum S, there beinganotherroil-bearing stratum S1 below the lower end of the casing 14. lnthe arrangement of the equipment shown in FIGURE 3, by continuedintroduction of the balls into the area of the casing perforations, asdescribed, while treating fluid is being forced downwardly through thecasing around the tubing, all of the perforations in the casing may besealed off, and thereafter, the open hole 4below the casing can `betreated =by the injection therein of acid or fracturing fluid throughthe lower end of the tub-ing, as is indicated by -the larrows 54. Withthis arrangement, positive treatment of the open hole below a casingwhich has been partially set through a producing formation, is providedfor.

In the embodiments described, when the treatment of the producingformations has been accomplished, the cage is removed from ythe well asthe tubing is elevated therefrom, and the upper end of the cage willengage the balls and retrieve all of them, the balls being againreceived in the cage and elevated thereby to the surface of the well. Bythe scratches, ridges and markings on the balls, it is possible todetermine how many of same were seated in the perforations and thusdetermine how many of the perforations were blocked off or closed by theIballs or spheres. It will be understood that the balls may be removedfrom the perforations mechanically, and without depending on a pressuredifferential between the formation and the interior of the casing, tosecure their removal. The balls may be made of a material which will notbe destroyed by the treating fluids or acids, but a material may lbeselected which will to some extent be reacted upon by the uids, in orderto show how many of the balls were present in the perforations, during atreating operation. Those skilled in the art will understand that it maybe of importance to determine if all of the perforations were closedolf, or to determine ust how many of the perforations were closedduring. a formation-treating operation. The material from which theballs may be made, will be a matter of selection.

They may be madek of appropriate metals, such as steel, aluminum, orappropriate alloys of these or other metals, of plastic, or of hardrubber, and the like. They should be of such weight that when the basketis positioned adjacent the perforations, as illustrated in FIGURE 2, acirculation of fluid downwardly through the tubing will elevate them toposition-s adjacent the perforations, in order that they may enter theopen perforations under the influence of the treating lluid passing intothe perforations, as illustrated. Of course, the balls should be of amaterial 4heavy enough to cause them to remain in the cage, by gravity,as the equipment is being lowered into the well, possibly throughaccumulated fluid in the well. The cage or basket C may be made of steelor steel alloy, or it may be made of plastic, aluminum, or othermaterial capable of being drilled out, or dissolved by acid, in case itshould become necessary to leave the cage in the well, such as in theevent that it should become stuck in the casing.

The o-peration of the embodiments referred to above will be clear fromthe description which has been given, but it is briefly summarizedbelow. The basket is screwed onto the bottom of a conventional oil welltubing and then filled with the desired number of balls or pellets, atthe surface of the well. Thereafter, the tubing is lowered throughwhatever equipment may be provided on the well, and down through thecasing to a point adjacent the lower end thereof, and preferably justbelow the perforations through which the treatment is to be made. lf anyof the balls are dislodged `from the basket during the descent, no harmwill result, for they will soon settle into the cage when its descenthas been arrested, and before treatment commences. The upper end o-f thetubing is connected to any appropriate hydraulic pump, as commonly usedon oil wells, and this pump may be operated to force the ball seatingfluid downwardly through the tubing, and thence upwardly from the lowerend thereof through the openings in the basket, to dislodge the ballstherefrom and elevate them to positions adjacent the perforations, andinto the range of the treating fluid. It will be understood that thetreating uid may be forced downwardly in the space between the casingand the tub-ing. This Huid may be admitted into this space through .anyof the appropriate outlets from the casing head equipment, such asthrough the side outlet 6@ in the casing or tubing -head 16, and it ispumped downwardly under the desired pressure, with available pumpingequipment and in a manner well known in the art. The treating fluidpasses through the open perforations and accomplishes acidifying orfracturing of the formation opposite these perforations, as is wellunderstood by tho-se skilled in the art. The introduction of thefracturing uid or acid through the casing perforations creates a flowpattern or current which causes the balls which have been elevated toproper position to enter the casing perforations and seal them off. Assome of the casing perfo-rations are sealed oli, the treating fluid is`forced by the pump pressure at the surface into the other perforationswhich have not been closed by the b-alls. Further uid may be pumped-through the tubing to move more of the balls into position to close offthe perforations. It will be understood that the method referred to maybe repeated or varied, within the skill or knowledge of the operator, tocause all of -the casing perforations to be sealed off by the ballmaterial. In general, when all of the perforations have been closed, itis established that all of the perforations and adjacent openings in theformation have received the treating fluid, so as to improve thecharacter of the formation adjacent to the perforations, for theproduction of oil and gas. Thereafter, the basket may be elevated toremove the balls from the perforations, in order that the well may -owor produce, under pressure of the formation, as is well understood inthe art. As previously stated, the equipment is so designed withrelation to the diameter of the casing in which it is used, that all ofthe balls can be removed with the basket, and subjected to inspection,in order to determine the effectiveness of the formation treatment whichhas been carried out.

As previously referred to, the open hole below 4the casing in certainwells having saine, can be treated by the injection therein through thetubing of acid or fracturing uid, after the casing perforations havebeen closed olf,

by practicing the invention as described herein.

It will be understood that the equipment described herein may be used inassociation with other conventional oil well devices, commonly employedat the surface of the well, or at the lower end thereof, such as packersand the like. The manipulative steps referred to herein may be varied,for purposes which best suit the situation which is encountered in thewell being produced, and the placing or removing of the balls may becontrolled at will, and from time to time as desired, in order to sealoff all or any part of the perforations, as may be required. Forinstances, the basket may be placed at any point of a perforated Izoneor area of a casing, in order to close off only the perforations atpoints above where the basket is positioned. Other manipulativevariations will occur to those skilled in the art in order to otherwisecontrol the manner of treatment of the perforations, and the formation.

I claim:

l. Apparatus for separating perforations in the casing of a wellcomprising: a cage having means for attachment to a tubing or other pipestring above the lower end thereof for sealing an area of the casinghaving perforations therethrough, said cage being of a size tosubstantially till the casing and open at its upper end, a plurality ofclosure pellets in said cage for upward discharge past the upper end ofsaid cage, -said cage have openings adjacent its lower end for upwardHow therethrough of -uid discharged 1from the lower end of the tubing,whereby circulating fluid may pass upwardly through said cage to elevatethe pellets therefrom into position to seal said perforations.

2. A. construction in accordance with claim 1, in which said pelletscomprise spheres made of metal or the like, and of size to close theperforations in the oil well casing without passing into or through saidperforations.

3. A construction in accordance with claim 1, wherein the upper end ofsaid cage removes the pellets from the perforations in the casing andreceives them into the interior of the cage when the cage is movedupwardly in the casing.

4. A construction in accordance with claim l, in which the upper end ofsaid cage is provided with means to attach an additional `sectionthereto to increase the pelletcarrying capacity of the cage.

5. A construction in accordance with claim l, in which the side walls ofthe cage have openings therein to permit ow of fluid inwardly throughthe wall of the cage to assist in elevating the pellets therefrom.

6. The method of treating the formation of a well below a perforatedarea of the casing which comprises, lowering under positive control aplurality of closure pellets of size to close the perforations withoutpassing into or -thru same to a level adjacent to and below theperforations to be sealed, elevating the pellets by forcing a lluidupwardly past the same, pumping the fluid outwardly thru theperforations to treat the formation and carry the` pellets into theperforations to close same, and forcing fluid downwardly in the well andoutwardly into the for-mation at an elevation below the area where theperforations have been closed by the pellets, and thereafter elevatingthe pellets under positive control `and raising the same to the surface.

7. The method of sealing perforations in a well casing comprising thesteps of lowering a cage `carrying a plurality of closure pellets of asize to close the perforations Without passing into or through the same,`to a level adjacent to and below the perforations to be sealed;circulating uid upwardly from below the plurality 0f pellets and throughthe cage with suicient pressure to carry the pellets upwardly intoposition to seal the perforations in the cage; and raising the cage topositively disengage the pellets from the perforations by engage- UNITEDSTATES PATENTS 2,698,582 Vincent Jan. 4, 1955 2,699,212 Dismukes Jan.11, 1955 2,754,910 Derrick et al. July 17, 1956 2,809,013 Ledgerwo-od etal. Oct. 8, 1957 2,868,509 Williams Jan. 13, 1959

